Lighting apparatus



March 29, 1927.

S. F. ARBUCKLE Filed April 30. 1924 LIGHTING APPARATUS 3 Sheets-Sheet 1 Samuel F Arbuc/r/e ATTO March 29, 1927. 1,622,938

s. F. ARBUCKLE LIGHTING APPARATUS Filed April 50. 1924 3 Sheds-Sheet 2 INVENTOR Samuel E Arbuc/r/e I 1 622938 March 29, 1927. s F. ARBUCKLE LIGHTING APPARATUS Filed April 50, 1924 3 Sheets-Sheets Z0 32. EL 36 34 g y 37 W30 j 38 1 INVENTOR Samuel Ell/"buckle ,,,,,4/ I, M W ATTYS Patented Mar. 29,1927;-

UNITED STATES PATIENT OFFICE.

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A CORPORATION OF DELAWABI.

LIGHTING APPARATUS.

Application fled April 80, 1924. Serial No. 708,981.

This invention relates to lamps, particularly such as are usable in connection with automobiles for road illumination.

In providing illumination for movable vehicles, there are several important and (le sirable requisites which should be consicL cred. One of these requisites is that the light provided does not cause what is known as glare, that is, a concentrated intensity of illumination which makes it diflicult for an approaching observer to see nearby objects clearly, observer and driver of the vehicle. Another important consideration is that illumination be provided commensurate with the speed at which a vehicle is traveling, it being desirable to have light at a' greater distance from the vehicle when the same is moving at high speed than is necessary when the vehicle is moving at slow speed. Heretofore, certain of these requirements have been met by such methods as tilting the reflector of the lamp so that the height of the beam is constantly under control by the operator and varied in accordance with the speed of movement of the vehicle and when approaching pedestrians or other vehicles. Certain of these requirements have been met also by the use of so-called dimming devices '30 in which the intensity of illumination is controlled by varying the intensity of light illumination, by providing a special type of light distributing lens, by forming a reflector so as to diffuse the light as reflected therefrom, or by the employment of other means. It is an important object of my invention to provide means for varying the distance in front of the vehicle at which effective illumination is possible,--thus fulfilling one 40 of the requirementsof variable speed driving, A second important object of the invention is to provide means in a lamp for automobiles or other movable vehicles by means of which variation in the direction of the light beam from the reflector due to loading in the vehicle is readily compen sated. Another object contemplated is the provision of means for increasing not only the distance ahead of thecar at which illumination is obtained, but also relatively to increase the depth of the light beam for etl'ective illumination. An object, also, is the utilization of a two-filament lamp with thefilaments so related to the reflector and to each other that a practical system with 9.

thus involving danger both to the driving and depressed beam is obtained and s des red approximately equal intensities of illumination are obtained from either filament.

Broadly stated, the invention consists in providing in a lam having a reflector which is preferably para olic, an electric lighting bulb having preferably two filaments, one positioned above the other aiid each lying substantially in the focal plane of the reflector, either one or both of the filaments (prer'erably one at a time as will appear) bemg adapted to be lighted by the operator and both of said filaments being off-set from the axis of the reflector. The above objects and various other obects such as relate to details of construction and economies of manufacture are accomplished by the structure referred to above and specifically detailed in the following description and covered in the appended claims.

One embodiment of the invention which may be preferred is illustrated in the accompanying drawings, in which:

Fig. 1 shows a diagrammatic view of the reflector and lighting unit givingthe di'rection of light rays when the upper filament is energized; I

Fig. 2 is a view similar to that of Fig. 1 giving the direction of light rays when the lower filament is energized;

Fig. 3 is a view showing the lightpattern produced by the various filaments on a screen; 7 v

Fig. 4 shows a light pattern produced in conjunction with a retracting lens;

Fig. 5 shows the electrical connection to the lamp;

Fig. 6 illustrates adetailed lamp construction; and

Fig. 7 is a diagrammatic View of the light beams from the reflector.

Referring to the drawings. particularly Figs. 1, 2 and 6, I have shown an electric lamp bulb 10, en'lbodying my invention applied to a headlamp 11, which may be of ordinary construction, including a casin 12,

a reflector 13 positioned therein whic is preferably parabolic in contour and an electrical socket connection Men the axis of the lamp adapted to receive atone end an electric lamp bulb 10 and at the other end the plug 15 connecting, to the electric conduit 16. In front of the reflector and 119 supported by the annular rim 17 and reflector flange 18 is the lens 19 of the lamp.

The bulb 10 contains instead of the usual sin 1e filament, two filaments 20 and 21 bot of which are substantially in the focal plane of the reflector, one below the other, and both of which are off-set from the focal axis of the reflector, and the lower filament may be off-set to a greater degree than the upper. In actual practice, the amount of displacement of. the filaments from the axis is relatively small, in one instance, for example, the upper filament being displaced 3/64ths of an inch and the lower 5/64ths of an inch making preferably the distance between the filaments approximately 1/8th of an inch, the filaments being of. the concentrated type as shown, but it is obvious that within the confines of the invention, the degree of displacement of the filaments may be varied to meet such requirements as arise in ordinary illuminating problems. While it is advantageous, under some conditions, to provide filaments which will give equal illumination as, for example, two 21 candle power filaments as herein indicated which give satisfactory results, I have also found it particularly desirable to employ filaments emitting light of different intensities in the referred embodiment of the invention, the lbwer filament giving approximately 50% greater intensity than the upper. For example, I may employ 'an upper filament giving 21 candle power and a lower filament giving an intensity of about 32 candle power. The advantages of the specific placement of filaments and the variation in illuminating intensities will be brought out in the description following.

Fi 5 illustrates a mode of connecting the two f ilaments of the lam with a source of electrical energy. Each lhmp is preferably grounded as at 30, the ungrounded wire of the filament 20 being connected by a conductor 31 to the switch contact 32 in reach of the o erator and the filament 21 bein connecte by the conductor 33 to the switch contact 34. f

A switch 35 of such design as to make contact alternately either with contact 32 or 34 or both simultaneously is illustrated in the drawing. As shown, there is a contacting bar 36 which may be brought in conducting relation with the contacts 32 and 34 as above indicated, although it is apparent that any suitable type of switch may be used to make the connections the switch, a conductor 37 leads to the battery 38 and round 39, completing the circuit to the ffiaments.

The operation of the lamp will now be considered. Preferably, though 'it is not essential. as shown in Figs, 1 and 2, the reflector of the head lamp is set with a small permanent tilt so that for an automobile indicated. Frempositioned on a level, the focal axis of the reflector is inclined slightly toward the ground. If now, the upper filament 20 is energized, as indicated in Figures 1 and 7, light will be emitted in all directions, the rays impinging on the reflector where the focal plane intercepts the same as at 40 and 41, being projected outwardly parallel to the focal axis. Since the filament is above the axis, rays impinging on the reflector behind the focal plane are projected downwardly. as indicated, for example, by the rays 42 and all rays impinging on the reflector surface in front of the focal plane are given an inclination diverging upwardly from the focal axis, as indicated by rays 43. Depending upon the depth of the reflector, it is evident from the above that a larger proportion of the rays of light from the upper filament are reflected downwardly from the axis of the reflector than are reflected upwardly, where the filament is above the lamp axis. Consequently, the effect of the light rays from the upper filament is to produce an image on a light screen at a distance in front of thevehicle, the average intensity of which is below the horizontal plane of the axis as indicated in Fig. 3 where 46 indicates the axial plane of the reflector and 47 in full lines the light pattern produced by the upper filament. It is, of course, obvious that the pattern 47, as shown in Fig. 3, is indicative only of the greatest concentration ,of the illumination, and does not define the total light radiated from the upper filament, the illumination gradually diminishing from the area 47 of greatest intensity.

If now, the upper filament is disconnected and the lower filament connected with the energy source, as illustrated in Figures 2 and illumination will he produced above the lamp axis, causing emission of light and reflection from the reflector to produce the pattern 48, as shown in Fig. 3. In this case, light rays impinging on the surface of the reflector back of the focal plane are reflected outwardly and upwardly relative to the axis, as indicated by rays 44, and the light rays contacting with the reflector in front of the focal plane being reflected downwardly relative to said axis, as indicated by re s 45, the general distribution of intensity eing indicated by the light pattern 48 of Fig. 3. It is pointed out that inasmuch as the lower filament is further. below the axis than the upper filament is above the axis. the light beam from the lower filament will have a somewhat greater depth through the area of greater intensity, this being due to the fact that the angle of incidence of light beams from a point in the focal plane of the reflector relative to the surface of the reflector will increase as the point moves away from the axis and hence the angle of reflection will become greater and the light pattern increased in width.

The manner in which the two filament lamp is used in actual practice will now be indicated. For ordinary driving conditions within city limits and with the car lightl loaded the upper filament will be lighte thus throwing the light rays in front of the car at such a distance as to suflice for ordinary city driving, providing illumination directly in front of the car. In country driving, however, especially where the speed of the automobile is increased to such a point that'light from the up er filament is too close to provide the required'amount of road illumination, the operator disconnects the upper filament and connects the lower filament 21, which because of its greater displacement from the axis of the lamp and its position below the axis, and also because of its greater intensity, compensating for its greater displacement if different candle powers are used although the same .candle power for each filament may be advantageously used as clearly indicated above, illuminates a stretch of the road considerably further in front of the car, thus enabling the driver to proceed without undue risk. If the illumination secured from the lower filament is insufficient for observation relatively close to the front of the car, which might occur under extreme conditions, both filaments are energized thus securing the requisite amount of light for operation.

\Vhere the reflector has been set relative to the axis of the car with the light load, it is evident that the adjustment will be displaced when the rear of the car is heavily loaded, the reflector axis being in this main ner tilted upwardly. Moreover, when the automobile is moving over the crest of a hill, the road-bed curves more rapidly than the (-ar, thus causing the light beams to shoot out above the road preventing proper illumination in front of the car. Both of these difficulties are obviated in the use of my invention by employing as a source of illumination. the upper filament of the lamp by means of which thelight beams are brought down to the road surface at a point relatively closer than that secured from the lower filament. Since by means of the switch 35 energization of either filament is under' control of the operator. proper adjustment of the road illumination may be had under all of the varying driving conditions above mentioned.

A feature of the invention, as described above, is that by displacing both filaments .from the focal axis, it is possible to get light-patterns from the reflector 1n which the average intensity of illumination is ap proximately the same. The advantage of this arrangement is evident on consideration of the fact that if one filament were at the focus of the reflector, the intensity of illumination from this filament would be disproportionately greater than that derivable from another filament off-set from the axis, due to the fact that the focal rays are concent-rated by the parabolic surface of the reflector. Moreover, the greater displacement of the lower filament from the axis permits a greater spread'of illumination relative to the direction of car movement than would be the case if both filaments aver-e equally displaced and since at higher driving speeds it is desirable to have not only more distant illumination, but illumination over relatively greater area, the increased displacement of the lower filament accurately meets operating conditions. It is pointed out further that by providing a lower filament of greater candle power than that of the upper filament, the diminution of intensity in the reflected light due to a further displacement from the axis is compensated although such further advantageous arrangement need not be used as indicated above and filaments of equal. intensity suffice when properly located. It is thus apparent that without the necessity of mechanically shifting the reflector, a control over the illumination in front of the observer is obtained which is equal to or superior to that secured by the tilting operation, enabling the construction of fixed units Withoutmoving parts subject to'improper adjustment and operation. This is particularly desirable on account of the increased amount of direct light derived from the 32 candle power filament when such filament is used and also arising from use at times of two filaments giving a total of 53spherical candle power which would create a light in certain atmospheric and driving conditions while direct light would be a menace to approaching drivers and also to the driver ofthe car on which the light is mounted.

In the above description, in order to bring out the operation of the filaments, reference to the lens 19 has been avoided. A function of the lens is to spread the light beam and it is therefore advantageously combined with the lamp to produce the most etlicient illumination.

In Fig. 4, there are shown light patterns 50 and 51 from the lamp produced by the upper and lower filaments, respectively, and reflected through a lens such as described and claimed in my co-pending application, Serial .No. 648,873, filed July 2, 1923, in which the light beam is spread laterally relative to the vehicle and intensified adiacent the-central portion of the beam. The elevation of the light beam and the deepening of the same is analogous to that secured where no lens is used but a further advantage of the lateral spread of light is maxi is obvious that other uses are possible and advantageous. I may, for example, use my lamp as a stationary source of illumination adapted to give a light beam of similar intensity but adjusted for different distances and without the use of movable reflecting or retracting devices. I may also use my lamp in combination with various shielding elements for cutting off the unreflectcd light emission as described in my co-pending a plication, Serial No. 688,947, filed January 28, 1924.

Another important and valuable feature of the invention is that of utilizing as a normal driving light a filament slightly displaced above the lamp axis. llns displacement is such as to lower the lower boundary of the beam but a slight variation in the position of the center of the. filament above the lamp axis will not effect the upper boundary of the light beam. There is, therefore, no problen'i of glare, inasmuch as since the upper boundary of the light beam is rilatively fixed, a slight modification of the lamp in the reflector due to accidental displacement or improper setting will have practically no effect on the upper light boundary and the necessity of complicated aml expensive adjusting necluinism is unnecessary.

I may also employ advantagcously in conjunction with my invention certain modified types of reflector such as the fluted type in which light spread is secured by staggering vertical parabolic sections of the reflecting surface.

'lhese and other uses and various structural modifications will be apparent to those skilled in the art to which the invention pertains, and I therefore desire to cover the invention broadly as well as specifically as indicated by the claims hereto appended.

I claim- 1. In a vehicle headlight, the combination of a reflector, a light source including a plurality of filaments of unequal candle power, lying on opposite sides of the axis of the reflector at unequal distances therefrom, and substantially in the focal thereof, the filament of greater candle power being placed below the axis and at a greater distance therefrom than the other filament, and means to energize either the lower filament to produce a forwardly directed beam of light of full intensity illuminating effect for distant lighting, or the upper filament to depress the portion of greater intensity of the beam of light to illuminate the road close to the vehicle, with a beam of light of substantially the same illuminating effect.

2. In a vehicle headlight, the combination of a casing, a reflector mounted therein and having its axis inclined downwardly, a light source having two filaments of unequal candle power, and arranged inside the reflector substantially within the focal plane, and on opposite sides of the focal point, the filament of greater candle power lying below the focal point and at a greater distance therefrom than the upper filament. and meansv to energize the lower filament to proplane I cct rays of light; upwardly with respect to the, axis of the reflector for distant lighting, or to energize the upper filament to cause a depression of the portion of greater intensty of the beam of light to illuminate the road close to the vehicle with substantially the same illuminating effect.

3. .ln a vehicle light projector, a reflector; a light bulb having two concentrated filaments spaced approxin'iatcly 1/8 of an inch apart aml lying substantially in the focal plane thereof, the lower filament being up proximately 5/64 of an inch from the focal point; and means to energize either filament at will to produce two distinct: beams, one for distance and one for near illumination.

4-. In a vehicle light projector, a reflector; a light bulb having two concentrated lilamcnts lying substantially in the focal plane of the reflector, one above and one below the focus of the reflector, the lower filament being placed up to and not over 5/64 of an inch below the focal point; and means to energize either filament at will to produce two distinct beams, one for distance and one for near illumination without substantial contrast in illumination of the roadway.

In testimony whereof, I affix mv signature.

SAMUEL F. ARn'UoKLn. 

